class_docstr: This :class:`Metric` takes the best span string computed by a model, along with the answer
  strings labeled in the data, and computed exact match and F1 score using the official SQuAD
  evaluation script.
code: def reset(self):
      self._total_em = 0.0
      self._total_f1 = 0.0
      self._count = 0
  
file_path: magnitude/pymagnitude/third_party/allennlp/training/metrics/squad_em_and_f1.py
imports: from __future__ import division
  from __future__ import absolute_import
  from allennlp.common import squad_eval
  from allennlp.training.metrics.metric import Metric
label_desc: Use image node_id 4 for calling the SquadEmAndF1 obj's underlying member method code with example usage: obj.reset() without return types